Both Sony A7R II and Sony RX1R II have Full frame sized 42.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Another similarity between these two cameras is that both Sony RX1R II and Sony A7R II sensors lack anti-alias (Low-Pass) filters. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moire occurring in certain scenes.
Below you can see the A7R II and RX1R II sensor size comparison.
Sony A7R II and Sony RX1R II sensors have exactly the same size so none of them has any advantage over other in this area.